The disclosed embodiments relate to wireless devices and wireless communication networks, and more particularly, to apparatus and methods for determining an estimated geographical position of wireless devices corresponding to events associated with wireless devices on a wireless network.
Many wireless communications devices, such as mobile phones, pagers, handheld computers, etc., have the ability to determine the location parameters associated with the geographical position of a wireless device on the surface of the earth. The location parameters may include the position and speed coordinates for the wireless device. The wireless device may include a geographical position location system in the form of hardware, software and/or firmware and other associated parameters.
One exemplary wireless device geographical position location system receives and analyzes location parameters derived from the Global Positioning System (GPS), a radio-navigation system, developed and operated by the U.S. Defense Department, that includes a series of 24 constellation satellites orbiting the earth at a distance of approximately 20,000 kilometers. The GPS position location parameters permit wireless device processors to determine their respective three dimensional positions and velocities using very precise location parameters and timing signals received from the satellites.
Determination of wireless device geographical position location is not limited to GPS. For example, wireless devices may employ a type of Assisted GPS, where the GPS position location parameters are combined with additional information related to the wireless network, such as position information from wireless network base stations, to increase the accuracy of the position location information. The additional information is particularly important in urban areas, where there may be attenuation, blocking and multipath fading of the GPS signal.
Unfortunately, there are other problems associated with the use of GPS and other position location information by the wireless device that have not been addressed. Each time a wireless device requests and retrieves position location information, the request and retrieval processing consumes a relatively large amount of wireless device power. Further, if the wireless device does not support simultaneous voice and data calls, then the device will not be able to get a location position during a voice call, or make a voice call during retrieval of a location position. Also, the period of time from when the wireless device makes a requests for position location information to when the wireless device receives the position location information may be significant, depending on such factors as the relative position of the wireless device to the location of the satellite, the speed at which the wireless device is traveling, the performance of the position location processing system of the wireless device, the type of position location system employed (for example, GPS, Assisted GPS, or other position location system), and the performance characteristics of the wireless device antenna. Such parameters may exacerbate the ability of the wireless device to accurately determine the geographical position location of the wireless device without draining wireless device power sources. The foregoing is particularly troubling when it is important to determine the position of the wireless device upon the occurrence of wireless device operational events, such as a call drop event on a cellular telephone.